As in, when you have a red light, the light is literally red — but when you have clothing that is dyed red, it’s reflecting red light. I thought originally that objects “reflected” color by their electrons absorbing all other colors and then emitting the color it was reflecting (in this case, absorbing all other wavelengths and emitting red). But then how does this set the object aside from a light source?
In: Physics
You are correct. The difference is that the red pigment doesn’t emit light unless there is light of the correct color shining upon it. When blue light hits a red object, it just gets absorbed and turned into vibrational energy. When red light hits a red object, the red light is briefly absorbed by the object’s electrons, then red light is reemitted back out. But if there is no red light shining on the object, the electrons don’t spontaneously emit red light. On the other hand, a red light source will emit red light on its own.
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